发送邮件：SMPT、MIME，是一种基于"推"的协议，通过SMPT协议将邮件发送至邮件服务器，MIME协议是对SMPT协议的一种补充，如发送图片附件等

接收邮件：POP、IMAP，是一种基于"拉"的协议，收件人通过POP协议从邮件服务器拉取邮件

账号准备：mail 客户端设置说明:参考官方Gmail帮助

一、依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><parent><artifactId>springboot-demo</artifactId><groupId>com.et</groupId><version>1.0-SNAPSHOT</version></parent><modelVersion>4.0.0</modelVersion><artifactId>mail</artifactId><properties><maven.compiler.source>8</maven.compiler.source><maven.compiler.target>8</maven.compiler.target></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-autoconfigure</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-mail</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-thymeleaf</artifactId></dependency></dependencies></project>

二、配置文件和启动类

application.properties

#这里以qq邮箱为例
# qq邮箱服务器
spring.mail.host=smtp.qq.com
# 你的qq邮箱账户
spring.mail.username=yourAccount@qq.com
# 你的qq邮箱第三方授权码
spring.mail.password=yourPassword
# 编码类型
spring.mail.default-encoding=UTF-8
spring.thymeleaf.prefix=classpath:/template/

@SpringBootApplication
public class DemoApplication {public static void main(String[] args) {SpringApplication.run(DemoApplication.class, args);}
}

三、MailUtil.java

@Service
public class MailUtils{// 日志private final Logger logger = LoggerFactory.getLogger(MailUtils.class);@Value("${spring.mail.username}") //注入 application.properties中指定的用户名private String from;@Autowired //用于发送文件private JavaMailSender mailSender;//发送普通文本邮件public void sendSimpleMail(String to,String subject,String content){SimpleMailMessage message = new SimpleMailMessage();message.setTo(to);//收信人message.setSubject(subject);//主题message.setText(content);//内容message.setFrom(from);//发信人mailSender.send(message);}//发送html邮件public void sendHtmlMail(String to, String subject, String content){//使用MimeMessage，MIME协议MimeMessage message = mailSender.createMimeMessage();MimeMessageHelper helper;try {helper = new MimeMessageHelper(message, true);helper.setFrom(from);helper.setTo(to);helper.setSubject(subject);helper.setText(content, true);//true代表支持htmlmailSender.send(message);logger.info("发送HTML邮件成功");} catch (MessagingException e) {e.printStackTrace();logger.error("发送HTML邮件失败：", e);}}//发送带附件的邮件public void sendAttachmentMail(String to, String subject,String content, String filePath){// 日志logger.info("发送带附件邮件开始：{},{},{},{}", to, subject, content, filePath);MimeMessage message = mailSender.createMimeMessage();MimeMessageHelper helper;try {helper = new MimeMessageHelper(message, true);//true代表支持多组件，如附件，图片等helper.setFrom(from);helper.setTo(to);helper.setSubject(subject);helper.setText(content, true);FileSystemResource file = new FileSystemResource(new File(filePath));String fileName = file.getFilename();helper.addAttachment(fileName, file);//添加附件，可多次调用该方法添加多个附件mailSender.send(message);logger.info("发送带附件邮件成功");} catch (MessagingException e) {logger.error("发送带附件邮件失败", e);}}//发送带图片的邮件public void sendInlineResourceMail( String to, String subject, String content,String rscPath, String rscId){// 日志logger.info("发送带图片邮件开始：{},{},{},{},{}", to, subject, content, rscPath, rscId);MimeMessage message = mailSender.createMimeMessage();MimeMessageHelper helper;try {helper = new MimeMessageHelper(message, true);helper.setFrom(from);helper.setTo(to);helper.setSubject(subject);helper.setText(content, true);FileSystemResource res = new FileSystemResource(new File(rscPath));helper.addInline(rscId, res);//重复使用添加多个图片mailSender.send(message);logger.info("发送带图片邮件成功");} catch (MessagingException e) {logger.error("发送带图片邮件失败", e);}}
}

四、邮件模板

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head><meta charset="UTF-8"><title>邮件模板</title>
</head>
<body>
您好，感谢您的注册，这是一封验证邮件，请点击下面的链接完成注册，感谢您的支持！<br>
<a href="#" th:href="@{http://www.bestbpf.com/register/{id}(id=${id})}">激活账户</a>
</body>
</html>

测试：

@RunWith(SpringRunner.class)
@SpringBootTest(classes = DemoApplication.class)
public class SpringBootApplicationTest {@AutowiredMailUtils mailUtils;@Autowiredprivate TemplateEngine templateEngine;/*** 指定模板发送邮件*//*** 指定模板发送邮件*/@Testpublic void testTemplateMail() {//向Thymeleaf模板传值，并解析成字符串Context context = new Context();context.setVariable("id", "001");String emailContent = templateEngine.process("emailTemplate", context);mailUtils.sendHtmlMail("zhaokuii11@163.com", "这是一个模板文件", emailContent);}/*** 发送简单纯文本邮件*/@Testpublic void sendSimpleMail() {mailUtils.sendSimpleMail("zhaokuii11@163.com", "发送邮件测试", "大家好，这是我用springboot进行发送邮件测试");}/*** 发送HTML邮件*/@Testpublic void sendHtmlMail() {String content = "<html><body><h3><font color=\"red\">" + "大家好，这是springboot发送的HTML邮件" + "</font></h3></body></html>";mailUtils.sendHtmlMail("zhaokuii11@163.com", "发送邮件测试", content);}/*** 发送带附件的邮件*/@Testpublic void sendAttachmentMail() {String content = "<html><body><h3><font color=\"red\">" + "大家好，这是springboot发送的HTML邮件，有附件哦" + "</font></h3></body></html>";String filePath = "your file path";mailUtils.sendAttachmentMail("zhaokuii11@163.com", "发送邮件测试", content, filePath);}/*** 发送带图片的邮件*/@Testpublic void sendInlineResourceMail() {String rscPath = "your picture path";String rscId = "001";String content = "<html><body><h3><font color=\"red\">" + "大家好，这是springboot发送的HTML邮件，有图片哦" + "</font></h3>"+ "<img src=\'cid:" + rscId + "\'></body></html>";mailUtils.sendInlineResourceMail("zhaokuii11@163.com", "发送邮件测试", content, rscPath, rscId);}
}